The present invention relates to a switch fabric architecture and related techniques for implementing rapid hitless switchover.
As the use of computer and telephone networks increases, so does the need for greater bandwidth. This need spurred the growth of fiber optic networks, and a protocol for transmitting data over such networks. As a result, the synchronous optical network or “SONET” fiber optic transmission protocol was developed.
FIG. 1 illustrates a functional block diagram of a conventional SONET network with add/drop multiplexors (ADMs) as nodes. A system administrator sets up connection routes through ADMs 110–140 to transfer data between endpoints, such as port A 100 and port B 150. For example, the system administrator may program a route from origination ADM 110 through intermediate ADM 120 to the destination ADM 130, and to do so, the system administrator must program necessary route information at each ADM.
Networks, however, do not remain static, and often must be altered to accommodate varying traffic flow. In which case, ADMs are typically reconfigured through a process known as “provisioning”, whereby existing connections are dropped while new ones are added. In relatively large networks in particular, provisioning can require an excessive amount of time because provisioning cannot be done automatically. Moreover, ADMs are typically rendered inoperable during provisioning, thereby increasing down-time for the network.